Powdered soap product



Patented May 10, 1949 POWDERED SOAP PRODUCT Joseph M. Tabor, Seibert, Mason, Bainbridge, Md.,

East Islip, N. Y., Howard F. Mich., and Paul R. Frohring,

assgnors to General Biochemicals, Inc., Chagrin Falls, Ohio, a corporation of Ohio Application January 24, 1946, Serial No. 643,122 1 Claim. (Cl. 2604-418) This invention relates to a method of directly producing a powdered soap product without the use of mechanical disintegration, and to the product so produced.

This application is a continuation-impart of our co-pending applications, Serial No. 506,060, filed October 13, 1943, (now Patent No. 2,440,029) and Serial No. 608,280, filed August l, 1945 (now Patent No. 2,461,300).

In these applications we disclosed a method and apparatus for extracting pigments, such, for example, as carotene, from fatty oils, in the course of which operation saponiable constituents of the oils were saponiiied. We discovered that if the saponication was carried out under certain conditions of operational sequence, temperature and pressure, and in the presence of certain organic solvents soap was produced in a useful, finely divided, powder form without the necessity and expense of any mechanical grinding, kneading, rolling or other disintegration method.

Powdered soap has commercial value both for use by the ultimate consumer and for use by soap manufacturers as a raw material for blending with fillers, extenders, abrasives, perfumes and the like in the production of various soap products. In the past, powdered soap has been lproduced by grinding or otherwise mechanically disintegrating a hard solid soap product. This has entailed expense. Furthermore, the physical character of many types of soap, particularly alkali metal soaps of vegetable oils, has been such as to make grinding difficult. Various ways have been proposed to overcome this diiculty. One method is disclosed in Patent No. 1,571,625 to George F. Dawes, in which moist soap is subjected to a relatively high temperature in a closed container-250-450 F. (121232 C.)- to cause the soap to swell up in the form of a light, porous mass which, it is alleged, can be readily powdered by rolling, kneading or crumbling.

It is one object of our invention to `provide a simple and economical method of producing a powdered soap product.

It is another object of our invention to avoid the difculties met in grinding soap by producing a powdered soap product directly without the need for mechanical disintegration.

It is a further object of our invention to produce a powdered soap product as a by-product of the extraction of pigments such as carotinoids from pigmented fatty oils.

According to our invention we treat a saponifiable fat or oil, which may advantageously be a pigment-containing oil, by intimately mixing the fat or oil with a regulated excess of an aqueous alkaline saponifying agent under heat and vacuum, continue the application of heat and vacuum until water is substantially completely removed from the reaction mass, agitate the mass further with a distillable organic solvent which is chemically inert to the reaction mass and in which the soap produced is substantially insoluble, withdraw the bulk of solvent in liquid form from the reaction mass, and evaporate residual solvent from the reaction mass under heat and vacuum while agitating the mass.

Under these conditions we have found that soap is produced in a dly, powdery condition, free of unsaponied oils, and suitable for use as a detergent or for additional blending or other manufacturing operations in the production of Various soap products. Furthermore, if the fatty material treated contains commercially valuable oil-soluble pigments such as carotene, these pigments are removed by the solvent in recoverable form; the relatively low temperature prevailing due to the Vacuum limits decomposition of theru mally unstable pigments and the production of malodorous pyrogenic compounds, thus adding substantially to the value of products.

Among the saponifiable materials which may be treated by our process we may mention palm oil, coconut oil, corn oil, soya oil, peanut oil, cotton seed oil, and neats-foot oil, but any oil or fusible fat, the fatty acids of which form a solid soap with a commercial aqueous alkaline saponifying agent, may be so treated.

Among the saponifying agents that may be used are sodium hydroxide and potassium hydroxide; such other basic compounds as are sufficiently -soluble and alkaline to saponify the oils treated as described below and have cations capable of forming hard soaps with the fatty acids of these oils may also be used. Fiftypercent caustic soda solution employed in 2 to 10 per-cent excess over theoretical requirements has been found a satisfactory saponifying agent but 20 percent or more excess may be used.

We prefer to carry out the saponification under such a vacuum that water is evaporated from the l'reaction mass at a temperature not above 80 C.; the required vacuum will vary depending on the concentration of the evaporating solution but in any event the pressure should not be allowed to exceed 355 millimeters of mercury, under which pressure water boils at C. The heat of the process and its saponication will ordinarily be suiiicient to evaporate most of the water from the saponication mass, but we have found it desirable to operate in a vacuum vessel provided with heating and cooling means such as a jacket, as well as with an agitator.

While we do not wish to be limited to any particular theory as to the success of our process, it appears to be largely due to the combination of vacuum operation and solvent treatment, with agitation during the saponication and during the evaporation of solvent. The internal heat of saponication is sufcient to boil off Water from the interior of lumps of soap-oil mixture under the low pressure obtaining, and this disrupts such lumps making them accessible to solvent action. The solvent completely removes any oil-soluble pasty, greasy unsaponiled material, whether or c not unsaponiable, which might act as a binder for the discrete powder particles. Furthermore, the evaporation of residual solvent eliectively removes azeotropically the last traces of water from the soap powder. Whatever the relative value of these factors is, the combined result is the production without grinding of a satisfactory dry powdery soap product.

The following example will illustrate our invention but is not intended to be taken in a limiting sense, the scope of our invention being defined Iby the appended claims.

The attached drawing, referred to in the iollowing description, is a diagrammatic flow sheet of our process.

Example .Iacketed rotary drier IB is charged with 1090 lb. palm oil, preheated to about 657 C., drawn from storage tanlr il through pipe l2 by means of suction applied by vacuum pump il through the pipeV connections shown with suitable manipulation of the valves in the pipe connections; horizontally rotating agitator (not shown) in rotary drier lll is set in operation and thereafter 319 lb. Sii-percent caustic solution, representing approximately 8.8 percent excess over the theoretical requirement, is similarly drawn into drier Ill from storage tank lil through pipe l5. The time required for charging the caustic soda is approximately to 15 minutes; during the charging a vacuum of 20 to 25 inches of mercury (250 to 125 mm. of mercury pressure) is maintained in drier Hi, and the temperature of the contents rises from 65 to 801 C. owing to the heat released by the saponication reaction. This heat is suilcient to heat any soap masses orlumps which are formed in which any substantial amount of pigment or unsaponied material is entrapped, and to vaporize the moisture in the newly formed soap lum-ps thus materially aiding in the drying and consequent progressive breaking up of the lumps which drying and breakin-g up continue until the soap is in the form of granules the bulk of which usually have a fineness of about l0 to 100 mesh.

The maintenance of reduced pressure in vessel I8 and the presence of water prevent a rise of temperature which would deleteriously affect the quality of the materials in the reaction mixture.

Thus in the present example, carotene decomposes at temperatures above 80 C. Accordingly during the saponification step the pressure is kept, suciently less than atmospheric pressure to insure the maintenance of a boi-ling temperature less than 80 C. For example successful results have been obtained usinga vacuum of about twenty-five inches of mercury (roughly 125 millimeters of mercury pressure). In the process of treating palm oil or other fatty material which will give a hard soap the pressure varies during saponication owing to the interaction of alkali with glycerides and consequent changes in the composition of the aqueous solutions, and therefore cannot be vstated in denite terms.

The employment of reduced pressures has the further advantages that it results in the exclusion from vessel Ill of air the presence of which would be detrimental since it would promote decomposition by oxidation ,of the carotene or other pigment being extracted, and facilitates the breaking down of newly formed soap lumps and the consequent freeing therefrom and recovery of pigment containing material, as Well as of free alkali and oil which may become entrapped in the soap lumps.

The Water vapor, ashed oi by the heat of saponication, #is withdrawn through vapor line 2t, dust trap 23, and line 22A into condenser 2| where it is condensed, and may be drawn ofi" and discarded when the saponication step is completed. This ordinarily requires about 1 to 11/2 hours, during which period the temperature is kept as continuously as possible at or below C. Agitation within vessel Hl is then discontinued and 550 gal. petroleum ether is transferred directly into the vessel il] from the solvent storage tank 25 through conduits 113 and 29 by means of pump 28. This is enough solvent to bring the level thereof, in vessel I6, up to the top of the rotary path of the agitator in this vessel. The vacuum having been released by opening valve mb, agitation isy continued for approximately fifteen minutes or until the soap is thoroughly wetted. When the solvent and soap have been intimately mixed, agitation s discontinued and the soap and the extract-bearing solvent are allowed to separate by gravity; When a solvent is used which has a specific gravity greater than soap the clear extract-bearing solvent is drawn of from the bottom of vessel Hl into the extract storage tank 3| through conduits 32 and 37, by means of pump 34. When the solvent employed has a specific gravity less than the soap, as is the case with petroleum ether, taps 32a are provided to draw the solvent from the top ofthe vessel.

When the extract-bearing solvent being withdrawn becomes cloudy as seen through line sight s in line 32, the withdrawal is stopped.

When all the clear extract-bearing solvent has been drawn out of vessel I0, fresh solvent for another wash is transferred into vesselv I0, in the manner set forth above, and agitation is resumed for approximately fteen minutes or until the remaining soap is again thoroughly wetted with solvent, after which the agitation is stopped, the soap and the extract-bearing solvent are again allowed to separate, and, after separation, the extract-bearing solvent is drawn off again, as described above.

The extracting step is repeated in this way four times to elect complete removal of any unsaponiied oily material and of pigment.

Vacuum is then again applied to vessel l0 and the. soap is freed of solvent under vacuum, vessel Ill being heated by admitting steam to its jacket, and its contents being agitated at. the same time. Evaporation of solvent completes the azeotropic vaporization of moisture from the soap. The last traces of solvent are then removed' by introducing dry steam under vacuum into vessel ID by steam-inlet pipe (not shown) agitation being continued for about nve minutes to insure mixing of the steam and soap. The solvent separated by the steaming step is recovered in the vacuum and atmospheric condensers 2l and 4B and receivers 39 and 48, respectively, from which lt is returned to solvent storage tank 25.

During the final step of drying the soap remaining in dryer l after the last solvent wash the operator should be on guard to detect and prevent foaming and should momentarily release the vacuum in vessel l0 by opening vacuum release valve Illb if foaming occurs.

After the extraction of the pigment from the oil, as described above, has been completed, the soap, which is now powdered and substantially pigment free, is removed from vessel I0, through dump doors provided for this purpose. The cycle of treatment in ves-sel I0 is complete when the soap has been discharged, and a new batch of oil may now be drawn into vessel I0 and the cycle repeated.

For each solvent wash approximately fifteen minutes is required until the soap is thoroughly wetted. The step of drying the soap, formed as a by-product of the extraction, usually requires about four hours when using in vessel I0 a vacuum of approximately 26 inches of mercury (roughly corresponding to 100 millimeters of mercury pressure). The over-all time required for the treatment of 1000 lbs. of palm oil from start to nish is about fourteen and a half hours.

As noted above, various modifications of the specific process of the example may be introduced in the practice of our invention with different saponiable fats and oils and with different saponifying agents.

Depending upon the characteristics of the particular kind of fat or oil to be treated we have found that it s usually desirable to employ more of the alkali solution than the chemical equivalent of the oil or other fatty material being treated. We have found that certain oils have a tendency to form a soft soap, and that a harder soap, and one having better powdering characteristics, may be obtained by using a substantial excess of alkali solution, the increased amount, over and above the chemically equivalent amount, being determinable by experimentation in each case. Thus, for example, we have found that in the treatment of palm oil we obtain very satisfactory results employing a twenty-percent excess of the aforesaid fifty percent aqueous caustic soda, but with effective agitation and careful operation a satisfactory powdered palm-oil soap product may be obtained with as little as 2 percent excess caustic soda.

The solvent extract containing oil-soluble pigment may be further worked up to recover salable 6 pigment as described in our above-noted copending applications.

Our soap product is a nely powdered product of bland, pleasant odor, low in or substantially free of oil-soluble pigments, containing a minor amount of free alkali and containing free glycerine released by the saponification. The glycerine may be separately recovered in further process steps or may be advantageously left in the product as a desirable ingredient.

We claim:

The process of producing a dry powdered soap product directly from a saponiable fatty material containing an unsaponiable oil-soluble ingredient, said fatty material being selected from the class consisting of fats and `fatty oils, which comprises: mixing said fatty material with an excess of aqueous saponifying agent in a closed saponication zone, agitating the saponication mixture, during the saponication maintaining in the saponication zone a pressure not greater than 355 mm. of mercury by exhausting therefrom gases and vapors evolved during the saponication, whereby the heat of saponication is utilized to boil off water entrapped in soap lumps formed during saponiflcation at a temperature substantially below the normal boiling point of Water and the lumps are thus disrupted and comminuted, continuing the agitation and maintenance of vacuum until the saponication mixture is substantially dewatered, extracting the dewatered mixture in the saponication zone with a solvent for the unsaponiable ingredient which is a non-solvent for soap, decanting the solvent extract from Ithe comminuted extracted soap. and removing yresidual solvent from the comminuted soap residue by vacuum distillation thereof with agitation in a current of dry steam, whereby a dry powdered soap product is produced.

JOSEPH M. TABOR. HOWARD F. SEIBERT. PAUL R. FROHRING.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,266,830 Taylor Dec. 23, 1941 2,271,406 Thurman J an. 17, 1942 2,318,747 Buxton May 11, 1943 2,318,748 Buxton May 11, 1943 2,345,098 Buxton Mar. 28, 1944 2,347,565 Kokatnur Apr. 25, 1944 2,380,410 Buxton July 31, 1945 2,383,631 Trent Aug. 28, 1945 

